Abstract: The invention relates to an inverter circuit for operating a speed-controllable asynchronous motor. The inverter circuit is of the type wherein the voltage and frequency are substantially proportional until the nominal frequency has been reached at nominal voltage. The circuit includes and inverter, a desired value control, a D.C. voltage supply with a voltage regulator which sets the voltage depending on the desired value, and a voltage-operated frequency regulator. The circuit can be operated at frequencies above the nominal frequency to avoid damage to the inverter which would otherwise be caused by (1) high voltage due to the motor operating as a generator or by (2) the rapid reduction of the speed setting controls which is not accompanied by a corresponding drop in the voltage supplied to the inverter.

Abstract: The invention relates to a fluid pressure operated motor or pump of the type having a gerotor displacement mechanism which normally includes inner and outer wheel and ring gears which in operation have relative rotational and orbital movement therebetween. Such devices inherently have a form of valving wherein, with a commutating type of action, fluid is directed from the casing inlet to expanding chambers of the gerotor and directed from collapsing gerotor chambers to the casing outlet. Two embodiments are presented in which the first has the casing thereof fixed in space. In both units the commutator valving includes valving patterns in two valve plates attached to opposite sides of the casing and in the wheel gear which has orbital movement relative to the casing.

Abstract: The invention relates to a control unit for an adjustable volume pump of the type having external controls for varying the volume output thereof. A pump for driving a hydraulic motor has the output pressure thereof increase as the motor load increases. The control unit hereof is responsive to the output pressure of the pump and regulates the pump controls to maintain a substantially constant volume through output for the pump despite varying load conditions on the hydraulic motor driven by the pump.

Abstract: The invention relates to a hydraulic planetary piston motor of the type having an externally serrated pinion gear which meshes with an internally serrated ring gear and has rotatable and orbital movement relative thereto. The unit has plate type distributor valving with fixed and moveable members and a piston, subject to control pressures on both sides thereof, for biasing the moveable valve member into sealing engagement with the fixed valve member. A change-over valve which may be pressure controllable functions to either cause biasing of the piston to effect the sealing mode or to relieve the biasing to cause a separation of the valve members to effect a short circuiting unloading thereof.

Abstract: The invention relates to refrigerator apparatus and particularly to the defrosting thereof. The thermostat is responsive to evaporator temperature and has first and second displacement ranges for respectively controlling the normal operation and the defrosting operation via first and second switches. A counter counts the cyclical operations of the first switch and at a predetermined count actuates an interrupter switch which is effective to block power to the compressor motor and direct power to the defroster heating apparatus. At a predetermined evaporator temperature the second switch is actuated which serves to reset the counter and this has the effect of ending the defrost cycle and returning the apparatus to normal operation under the control of the first switch.

Abstract: The invention relates to a hydraulic pump or motor having expansible chamber section at one end thereof, which may be a gerator gear set, and a drive shaft at the other end thereof. A distributor valve having a central bore directs fluid between inlet and outlet ports in the housing and the expansible chamber section. The leakage of pressurized fluid into the central bore of the valve causes certain problems including the problem of directly or indirectly causing destructive forces to be applied to the seal provided between the drive shaft and the housing. This problem is addressed by providing check valve arrangements in the housing between the central bore of the valve and the inlet and outlet ports. The check valves open in the direction of the inlet and outlet ports so that when fluid pressure in the valve bore exceeds the fluid pressure in either of the ports, the pressure in the bore is lowered by fluid being forced outwardly through the port having the lower pressure.

Abstract: The invention relates to a hydraulic pump or motor having inlet and outlet ports and expansible chamber section at one end thereof, which may be a gerator gear set, and a drive shaft at the other end thereof. A distributor valve driven by the drive shaft and having a central bore directs fluid between the inlet and outlet ports in the housing and the expansible chamber section. A shaft, such as a cardan shaft, disposed in the central bore of the valve provides a driving connection between the valve and the expansible chamber forming section. Although a bearing is provided in the housing for the drive shaft, the distributor valve is also subjected to radial loads because the cylindrical surface thereof has a close fitting sealing relationship with the housing bore in which it is rotatably disposed. Lubrication for both ends of the cylindrical surface of the valve is provided by passages extending from valve passages which carry the motive fluid controlled by the valve.

Abstract: The invention relates to a steering control system for a bidirectional servomotor connectable to steerable wheels. The servomotor may be of the differential type in which a rod extending from one side of the piston thereof causes the effective areas on opposite sides of the piston to be unequal. A steering control unit controlled by a steering wheel has two motor ports connected to opposite sides of the servomotor and pump and tank ports connected to pump and tank units. The steering control unit has a metering motor controlled by the steering wheel which meters fluid to and away from only one side of the servomotor. The steering control unit has oppositely acting valves which may be throttle valves for establishing flow paths for opposite steering directions and the neutral condition.

Abstract: A pressure responsive switching device, particularly a pressostat or thermostat, comprises an actuating element (5) which is loaded in one direction by an operating element (1) at the pressure and in the other direction by a main spring (9) by way of a force transmission device (10). The latter has a physical quantity (P.sub.k) which is variable with the force transmitted by the operating element. In addition, there is a measured value generator (23) which, depending on this physical quantity, delivers an electric analogue signal (S). The force transmission device may comprise a compensating force producer (10) in the form of an expansion element (15) which is provided with a liquid-vapor filling and a heating device (21), by which the compensating force of the force of the operating element (1) is made to follow. In this way, the switching device can deliver an analogue signal (S) corresponding to the system pressure (P) by using the same operating element (1).

Abstract: The invention relates to a motor driven reciprocating piston compressor of the type utilized for encapsulated small refrigerators. Valving for the valve plate between the piston and cylinder chamber provides automatic unloading when the gas in the cylinder chamber falls below a predetermined temperature in the 80 to 100 degree centigrade range to prevent pressure build ups in the cylinder chamber during idle periods which cause undesired high starting torques.

Abstract: The apparatus herein relates to an ultrasonic measuring device having a quadrupole circuit unit. Two ultrasonic converter circuits are alternately and complementary operable as transmitter and receiver circuits and have terminals on opposite sides of the quadrupole circuit unit. The quadrupole circuit unit has a transmission signal generator on the input side thereof and a receiver amplifier on the output side thereof. This kind have a zero point displacement which becomes noticeable by the fact that during a measurement in static liquid the measured signal has different values depending on the direction. As only one transmission signal generator and only one receiver amplifier are used, these values cannot be eliminated as is possible in the case of known constructions with two transmitters.

Abstract: The invention relates to a heating installation which includes a boiler and a heat pump. The heat pump has a multi-stage compressor. Graded threshold value operating switches for the multi-stage compressor and the boiler are provided. A control unit which includes comparator and integrator units functions to select compressor and boiler outputs in response to comparisons between indoor and outdoor temperatures made by the comparator unit.

Abstract: The invention relates to a hydraulic steering system of the type having a servomotor controlled by a steerable valve assembly which directs metered quantities of pressurized fluid to the servomotor and has a feedback arrangement for stopping the flow of fluid when the steering motion is stopped. The system involves an arrangement wherein the metering unit is arranged downstream from the servomotor and an auxiliary valve is provided for automatically accommodating normal conditions as well as emergency pump failure conditions and overpressure conditions caused by the servomotor reaching an extreme end position in the operation thereof.

Abstract: The invention relates to a control circuit for controlling the driving and braking current of a brushless type DC motor of the type having a permanent magnet rotor and a pair of poles provided with two windings, the windings having a common junction which is connectable to the positive terminal of a DC voltage source. The windings are double wound on the core of the motor stator and a pair of controllable switching elements are in respective series with the windings. A scanning commutating circuit responsive to the angular position of the rotor has dual outputs for switching the switching elements on and off in a push-pull mode. Free wheeling diodes are connected respectively to the junctions of the windings and the switching elements and first and second current measuring resistors are in respective series relation to the switching elements and the diodes.

Abstract: The invention relates to a device for producing a control pressure which corresponds to a rotary speed imparted to a shaft of a pump which is a part of the device. The device includes a measuring orifice formed by a fixed throttle and a control orifice formed by piston arrangement operating as a controlled throttle. The controlled throttle is responsive to oppositely acting pressures from opposite sides of the fixed throttle. The controlled throttle is in series with a fixed discharge throttle and the control pressure is tapped from between the controlled throttle and the discharge throttle.

Abstract: The invention relates to apparatus and a method for assembling a thermostatic type bellows unit of the type having a cup shaped bellows housing and disposed in spaced relation thereto a corrugated cup shaped diaphragm having a rigid annular flange. The assembling involves pressure welding the diaphragm flange to the housing. The apparatus includes a bottom electrode having a chamber for receiving and supporting the bellows unit and an upper electrode having a central projection which protrudes into the diaphragm and a surrounding collar for biasing the diaphragm flange into abutting engagement with the upper edge of the housing. A suction system including a passage in the electrode projection provides a partial vacuum for drawing the diaphragm into engagement with said upper electrode projection. The chamber is then flushed with a flushing medium.

Abstract: The invention relates to a hydraulic torque amplifier for steering devices or the like. The amplifier has a planetary type piston motor having a rotatable externally toothed inner gear and an orbitable, nonrotatable internally toothed outer gear. The amplifier has input and output shafts rotatably journaled in the amplifier housing in coaxial and axially spaced relation. The valving arrangement includes inner and outer sleeves with the input shaft being fixedly connected to the inner sleeve and the output shaft being fixedly connected to both the inner gear and the outer sleeve.

Abstract: The invention relates to a coil assembly and a method for making same. In particular the invention is directed to the attachment of a terminal pin to the coil assembly base plate and the connecting of the terminal pin to an end portion of the coil wire in a manner which lessens the chances of inadvertently breaking the coil wire.

Abstract: The invention relates to a method for making a thin walled diaphragm unit of the type used in pressostats and thermostats. The method involves attaching a ring element to one end of a tubularly shaped diaphragm element which may have the bellows forming corrugations formed thereon either before or after the attachment of the ring element. Electrodes are utilized for physically pressing the parts together as well as providing for a flow of current through the joint to provide a metallurgical joining of the parts. A layer of an alloy of phosphorous and nickel is applied to the ring element which results in a heat joining of the parts which in effect is between soldering and welding.

Abstract: The invention relates to a time switch assembly of the type having an electric stepping motor, a pulse generator and a connecting drive therebetween for driving the motor at speeds corresponding to the frequency of the pulse generator. A time plate is driven by the motor and a scanning switching circuit is responsive to different speeds of the time plate. First and second counters in series are provided between the pulse generator and the motor. A switching device between the counters provides selectable bypassing of the second counter so that the motor may be driven at a speed corresponding to the output of only the first counter or at a slower speed corresponding to a slower counter output of the two counters operating in series.